Cruise lines like to boast about their restaurants, cabins, spas and other amenities, but Royal Caribbean International’s new brand campaign calls attention to something else: the ocean its liners sail on.

The new pitch is: “The Sea is Calling. Answer it Royally.”

Using a conch shell called the “Shellphone,” a series of outdoor ads in six cities will lead to the website www.TheSeaisCalling.com starting Dec. 19. Television commercials will start Jan. 9 on CBS, Fox, ABC and national cable channels.

The campaign, announced Tuesday, replaces the old “Nation of Why Not” slogan, which a spokeswoman says did not resonate with international markets.

“We are tapping into the sea’s powerful, emotional force to reframe the context of cruising for consumers who don’t understand what a Royal Caribbean cruise vacation offers,” said Betsy O’Rourke, Royal Caribbean’s senior vice president for marketing, in a statement. “‘The Sea is Calling’ is a global-scale campaign that will resonate with people no matter where they live, what language they speak, or whether or not they’ve cruised before.”